fix: DB backup on schema change, MCP child cleanup, codex models, usage providers OOM

- Backup DB only on real SCHEMA_VERSION change, not every app version bump
- Kill idle MCP stdio bridge children to prevent orphan process leaks
- Add getDistinctProviders to avoid loading every row JSON blob (OOM fix)
- Update codex model list (gpt-5.6 sol/terra/luna, drop 5.3 codex variants)
- Reorder Claude default models (fable first)

Co-authored-by: Cursor <cursoragent@cursor.com>

src/app/api/usage/providers/route.js

@@ -1,5 +1,5 @@
 import { NextResponse } from "next/server";
-import { getRequestDetails } from "@/lib/requestDetailsDb";
+import { getDistinctProviders } from "@/lib/requestDetailsDb";
 import { getProviderNodes } from "@/lib/localDb";
 import { AI_PROVIDERS, getProviderByAlias } from "@/shared/constants/providers";
 
@@ -9,10 +9,9 @@ import { AI_PROVIDERS, getProviderByAlias } from "@/shared/constants/providers";
  */
 export async function GET() {
   try {
-    const { details } = await getRequestDetails({ pageSize: 9999 });
-
-    // Extract unique providers
-    const providerIds = [...new Set(details.map(r => r.provider).filter(Boolean))].sort();
+    // Query DISTINCT provider column directly — avoids parsing every row's
+    // full JSON blob (can be hundreds of MB), which previously caused OOM.
+    const providerIds = await getDistinctProviders();
 
     const providerNodes = await getProviderNodes();
     const nodeMap = {};

src/app/api/usage/request-details/route.js

@@ -9,8 +9,10 @@ export async function GET(request) {
   try {
     const { searchParams } = new URL(request.url);
     
-    const page = parseInt(searchParams.get("page")) || 1;
-    const pageSize = parseInt(searchParams.get("pageSize")) || 20;
+    const pageRaw = parseInt(searchParams.get("page"));
+    const page = Number.isNaN(pageRaw) ? 1 : pageRaw;
+    const pageSizeRaw = parseInt(searchParams.get("pageSize"));
+    const pageSize = Number.isNaN(pageSizeRaw) ? 20 : pageSizeRaw;
     const provider = searchParams.get("provider");
     const model = searchParams.get("model");
     const connectionId = searchParams.get("connectionId");